Drain safety device



June 1970 D. D. HARDINGHAM 3,516,541

DRAIN SAFETY DEVICE Filed Nov. 7. 1968 I N VENTOK DEREK D. HARDING/4AA,

United States Patent Oihce 3,516,541 Patented June 23, 1970 3,516,541 DRAIN SAFETY DEVICE Derek D. Hardingham, Long Beach, Calif., assignor, by direct and mesne assignments, of fifty percent each to David D. Coles and Donald M. Moss, Newport Beach,

Calif.

Filed Nov. 7, 1968, Ser. No. 773,983 Int. Cl. B01d 35/02 U.S. Cl. 210-164 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention A prefabricated drain safety device adapted to be mounted in a vertical drain structure to prevent upward discharge of explosive vapors through the structure into the ambient atmosphere.

Description of the prior art In refineries and other industrial installations having extensive hard-surfaced working areas it is common practice to provide underground drain lines which communicate with spaced, downwardly extending drain structures. Occasionally, volatile hydrocarbon liquids are discharged into such drain lines. The vapors generated from such liquids mix with air in the drain lines to form an explosive mixture that is in communication with the ambient atmosphere through the drain structures. In the past, it has been necessary to cover the inlets to all such drain structures with sandbags prior to performance of welding operations, or the like, to avoid possible ignition of any explosive vapors in the drain lines with the usual accompanying disastrous results. Sand bagging of drain structures is expensive, yet does not assure complete protection against fire should explosive vapors in drain lines accidentally ignite.

The present invention overcomes the disadvantages of sand bagging of such drain openings by the provision of A prefabricated drain safety device incorporating a rigid sheet in which a central opening is formed that is in communication with a depending cylindrical shell that is housed within an apertured tank secured to said sheet. The peripheral edge portions of the shell rest on body shoulders forming a part of a downwardly extending drain structure. A grated frame rests on the upper surface of the sheet and removably holds the safety device in place on the upper portion of the drain structure.

After installation of the safety device, water is discharged thereinto until it flows from the apertures in the tank, which apertures are located above the lower edge of the shell. Thereafter a body of water is contained in the tank, which serves as a seal to prevent discharge of explosive gases from an underground drain line.

A major object of the present invention is to provide a prefabricated drain safety device of relatively simple mechanical structure which can be fabricated from standard, commercially available materials, is easy to install,

-weight, easily portable drain safety device of a bright distinctive color which visually indicates that a particular vertical drain is protected by a water seal against discharge of explosive gases into the ambient atmosphere.

A further object of the invention is to supply a safety device of relatively lightweight structure that is formed from fibers of glass impregnated with a polymerized resin, which device is particularly adapted for removable installation in an existing vertical drain provided with a horizontal body shoulder in which an iron grating rests, with the safety device when so installed being substantially impervious to the action of water and moisture, and with only the peripheral edge portion of a sheet forming a part of said device being subjected to the wheel load of a vehicle as it passes over said grating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a first form of the drain safety device;

FIG. .2 is a vertical cross-sectional view of the device, taken on the line 22 of FIG. 1;

FIG. 3 is a transverse cross-sectional view of the device, taken on the line 3-3 of FIG. 3;

FIG. 4 is a perspective view of the upper portion of a drain structure after the safety device has been installed therein;

FIG. 5 is a vertical cross-sectional view of the device, taken on the line 5-5 of FIG. 4; and

FIG. 6 is a perspective view of a second form of the drain safety device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first form of drain safety device A, best seen in FIG. 1, includes a rigid sheet B in which a central opening 10 is formed that serves as an entrance to a depending cylindrical tube or shell C. A tank D (FIG. 2) is provided, from the upper edges of which a circular flange 12 projects outwardly and is bonded to the lower surface of sheet B.

Tank D is substantially greater in depth and transverse cross section than the shell C, as may be seen in FIG. 2. One or more second openings 14 are formed in tank D, located above the lower edge of the shell C. The combined area of the openings 14 is preferably at least equal to the interior transverse cross section of the shell C in order that downward flow of fluid through the drain safety device A will not be impeded.

Sheet B, shell C, and tank D are preferably fabricated from resin impregnated glass fibers, although other materials resistant to moisture, water, and anti-freeze compounds may be used for this purpose if desired. Each drain safety device A is prefabricated and delivered to the site where it will be installed in the form shown in FIG. 1.

Sheet B includes an annulus-shaped area 16 that slopes inwardly toward shell C to facilitate the flow of surface water into tank D. The tank D includes a cylindrical side wall 18 and bottom 20. A typical downwardly extending drain structure B such as found in existing refineries is shown in FIG. 5, and includes a continuous wall 22 which defines an interior, vertical passage 25 leading to an underground drain line (not shown).

Wall '22 is recessed at the top, as illustrated in FIG. 5, to define a continuous horizontal body shoulder 24. The sheet B may be either formed to such size as to rest on the body shoulder 24, or if of too large area to so fit, the excess edge material may be trimmed from the sheet. The formed or trimmed sheet B is positioned on the 3 shoulder 24, and a grated frame F (FIGS. 4 and 5) is then placed in the recessed portion 26 of the 'drain structure E. The edge portions of the sheet are thereafter sandwiched between the frame F and body shoulder 24. If desired, a mastic material G or other sealant can be applied to the upper and lower edge surfaces of the sheet B to seal with the body shoulder 24 and frame F.

After installation of the drain safety device A, water is discharged into the device until it overflows through the second opening 14. A body of water 28 remains in the tank D to serve as a seal and prevent upward discharge of explosive gases through passage 25 into the ambient atmosphere. When the drain safety device A is used in such locations subject to freezing weather, salt or other anti-freezing material may be added to the body of water 28 to prevent solidification thereof. The lower edge of shell C is located a substantial distance above the bottom to provide a space 30 in which solids may accumulate without obstructing communication between first and second openings 10 and 14.

A second form A of the drain safety device is shown in FIG. 6. This second form A differs from form A, only in that the sheet B is circular rather than square or rectangular. Elements of the second form A corresponding to like elements found in the first form A are identified in the drawing by the same numerals, but to which primes have been added. Both the first and second forms A and A, respectively, are preferably brightly colored to visually indicate that drain structures in which they are installed will not discharge explosive vapors into the ambient atmosphere.

The use and operation of the invention have been described in detail previously, and need not be repeated.

I claim:

1. In combination with a grated frame that rests on a continuous recessed horizontal body shoulder of an existing vertical drain structure that is in communication with an underground line in which explosive vapors may accumulate, a safety device to prevent discharge of said vapors into the ambient atmosphere, which safety device includes:

(a) a sheet of rigid material disposed in the upper portion of said drain structure said sheet being so constructed and arranged that it may be readily cut and adapted to fit into various size existing drain openings, with the peripheral edge of said sheet being sandwiched between said body shoulder and said grating, and in which sheet a first opening of substantial size is formed;

(b) a cylindrical tube depending from said sheet into said drain structure and in communication with said opening; and

(c) a tank of substantially greater transverse cross section and depth than that of said tube, which tank depends from said sheet surrounding said tube, with said tank having at least one second opening in a side portion thereof, with said second opening being disposed above the lower edge of said tube whereby after water has been added to said tank to the extent that it flows therefrom through said second opening the lower end of said tube is immersed in said water in said tank and acts as a seal to prevent discharge of said explosive vapors from said underground line into the ambient atmosphere, and said safety device only having the portion thereof sandwiched between said shoulder and grating subjected to a substantial compressive load when the wheel of a vehicle travels across said grating.

2. A drain safety device as defined in claim 1 wherein an annulus-shaped portion of said sheet surrounding said opening tapers inwardly toward said tube to facilitate the runoff of surface water to said underground line.

3. A drain safety device as defined in claim 1 wherein at least said sheet is formed from resin impregnated fibers of glass and is permanently bonded to said shell and tank.

4. A drain safety device as defined in claim 3 wherein said tube is formed from resin impregnated fibers of glass as an integral part of said sheet.

5. A drain safety device as defined in claim 1 wherein said sheet, tube and tank are formed as an integral unit from a rigid resin-containing material that is substantially impervious to the action of moisture and water.

6. A drain safety device as defined in claim 1 wherein the area of said sheet, prior to installation in said drain structure, is greater than the transverse crosssectional area of the latter.

7. .A drain safety device as defined in claim 1 wherein a plurality of second openings are formed in said tank, with the combined area of said second openings being at least as great as the interior transverse cross-sectional area as that of said tube.

8. A drain safety device as defined in claim 1 wherein the lower edge of said tube is sufiiciently high above the bottom of said tank that a substantial amount of solid material may accumulate in the lower portion of said tank without obstructing communication between said first and second openings.

9. .A drain safety device as defined in claim 1 wherein at least said sheet is of a bright, distinctive color to readily indicate that a particular drain structure is protected by said safety device.

10. A drain safety device as defined in claim 1 wherein said tube is circular.

References Cited UNITED STATES PATENTS 543,617 7/1895 Dunston 210-164 2,859,875 11/1958 Wilkie 210--163 2,695,678 11/1954 Sisk 210-165 3,411,628 11/1968 Mason 210-163 REUBEN FRIEDMAN, Primary Examiner T. A. GRANGER, Assistant Examiner 

